538 



THE CHANGING WORLD 



The short-legged orang-utans of Borneo and Sumatra, though 

 larger than gibbons, are likewise denizens of tropical forests, being 



more at home in the tree-tops 

 than on the ground. They 

 frequently build for them- 

 selves temporary nests or 

 shelters of sticks and twigs, 

 and exhibit an increased men- 

 tal capacity over that of the 

 gibbons. 



Probably the chimpanzees 

 of tropical Africa are the best 

 known of the apes because of 

 their teachability, and con- 

 sequent exploitation on the 

 vaudeville stage, at Holly- 

 wood, and elsewhere. In the 

 last twenty years. Dr. Robert 

 M. Yerkes of Yale University, 

 with a stafT of assistants, has 

 been studying intensively the 

 behavior of these disconcert- 

 ingly "almost human" apes, 

 maintaining for the purpose 

 a considerable colony of them 

 under constant observation in 

 Florida, and another smaller 

 group at New Haven, Connec- 

 ticut. His painstaking and 

 arduous investigations are 

 adding very much to our accu- 

 rate knowledge of the dawn 

 of intelligence and of the an- 

 cestral sources of human be- 

 havior. 



The gorillas of Africa are the 

 largest apes, and perhaps the 

 least known, because of their in- 

 accessibility and the difficulty of maintaining them in captivity. Their 

 strength is prodigious and their courage is said to be unbounded. 



A'rw York Zoological Society 



The gibbon and chimpanzee are representa- 



apes. 



tivcs of the 



